Cloud computing defines a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. Essential characteristics of the cloud computing model include on demand self-service, broad network access, resource pooling, rapid elasticity and measured service. The cloud computing model comprises several service models, including Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). The cloud computing model may be implemented according to one of the several deployment models, including private cloud, community cloud, public cloud and hybrid cloud.
Cloud infrastructure is a collection of hardware and software that implements the cloud computing model. Cloud infrastructure may be viewed as comprising a physical layer and an abstraction layer. The physical layer may comprise hardware resources designed to support the cloud services being provided, and typically includes server, storage and network components. The abstraction layer may comprise the software deployed across the physical layer, which manifests the essential cloud characteristics. Conceptually the abstraction layer resides above the physical layer.